Dihydrotestosterone, Free, Serum

Test Code

36168

CPT Codes
82642

Includes

Dihydrotestosterone and DHT, Free

Preferred Specimen

1.5 mL serum collected in a red-top tube (no gel)

Minimum Volume

1 mL

Transport Container

Transport tube

Transport Temperature

Refrigerated (cold packs)

Specimen Stability

Room temperature: 48 hours
Refrigerated: 7 days
Frozen: 6 months

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Moderate to gross hemolysis • Grossly icteric • Serum separator tubes (SST) • Plasma

Methodology
Equilibrium Dialysis • Chromatography/Mass Spectrometry

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by the U.S. Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

Set up: Tues; Report available: 3-11 days

Reference Range

Dihydrotestosterone
Females	≤20 ng/dL
Males	12-65 ng/dL
DHT, Free
Adult females	0.30-1.90 pg/mL
Adult males	1.00-6.20 pg/mL

Clinical Significance

This test measures serum concentration of dihydrotestosterone (DHT) and may help diagnose 5-alpha-reductase deficiency, an autosomal recessive condition that affects male sexual development [1]. Measurement of DHT levels has also been used to evaluate therapies affecting androgens levels.

DHT is the most potent androgen and plays an important role in male external genitalia development, prostate growth, and skin metabolism. DHT is largely derived from testosterone via 5-alpha-reductase activity in the peripheral tissues but can also be synthesized through a "backdoor pathway" without testosterone as a precursor [2]. Individuals with 5-alpha-reductase deficiency have diminished conversion of testosterone to DHT. Thus, an elevated ratio of testosterone to DHT may support the diagnosis. Definitive diagnosis of 5-alpha-reductase deficiency requires a DNA analysis of SRD5A2 [1].

Most circulating DHT is bound to sex hormone binding globulin (SHBG). Because SHBG levels can be altered by medications, disease, and sex steroids, measurement of free DHT more accurately reflects the level of bioactive DHT than measurement of total serum DHT.

Although DHT was implicated in prostate tumorigenesis circumstantially, current evidence does not support the association between elevated serum DHT levels and increased risk of benign prostatic hyperplasia and prostate cancer [1].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

Reference
1. Swerdloff RS, et al. Endocr Rev. 2017;38(3):220-254.

Performing Laboratory

Quest Diagnostics Nichols Institute-San Juan Capistrano, CA

33608 Ortega Highway

San Juan Capistrano, CA 92675-2042

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.